Treatment method of Ordovician limestone water based on hydrogeological exploration

Abstract

The present invention belongs to the field of hydrogeology, and specifically relates to a method for controlling Ordovician limestone water based on hydrogeological detection. The present invention corrects the calculation results of the bottom plate fracture zone depth based on hydrogeological detection, and comprehensively considers the lithology and layered characteristics of the rock strata, so that the corrected bottom plate fracture zone depth calculation results are more accurate, and the practical engineering application significance is stronger. It solves the problem of the existing technology of arbitrarily adding a certain thickness as a safety thickness without basis after calculation through a formula, and thus the present invention can more accurately determine the thickness of the aquifer. The present invention adopts a comprehensive control plan for the control of the confined aquifer - Ordovician limestone water, which integrates detection and pre-reinforcement, advance pressure relief, water interception and drainage, and each step of the control plan is constructed based on the actual hydrogeological detection situation, which improves the control effect of Ordovician limestone water and ensures safe production on the working face.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogeology, and in particular relates to a method for treating Ordovician limestone water based on hydrogeological detection. Background Art

[0002] Mine water inrush is one of the most threatening geological disasters in the coal mine production process. After the coal seam is mined, a goaf is formed at the mining location. As the mining scope increases, the goaf continues to increase, and the overlying roof rock layer will continue to collapse to form a caving zone and a water-conducting fracture zone from bottom to top. If there is a water-bearing rock layer in the water-conducting fracture zone, the rich water in it will enter the coal mining face from the fractures in the water-conducting fracture zone, forming water inrush. This is the most common water inrush disaster phenomenon and is also the focus of water inrush prevention and control research.

[0003] Another type of water inrush disaster comes from the Ordovician limestone water in the bottom of the coal seam. The Ordovician limestone water is the water contained in the limestone formed in the Ordovician period. This water-containing limestone layer is generally located in the lower part of the coal seam and is a pressurized aquifer. After the coal seam is mined, the bottom rock layer of the coal seam will also produce cracks due to mining stress and mining activities, forming a bottom mining fracture zone. If the bottom mining fracture directly reaches the Ordovician limestone water, since the Ordovician limestone water is a pressurized aquifer, when the pressure is sufficient to overcome the height of the Ordovician limestone water from the coal seam, the Ordovician limestone water will surge to the coal mining face and cause a water inrush disaster.

[0004] For the hazard of Ordovician limestone water, a confined floor aquifer, existing technologies offer methods for calculating the maximum depth of floor mining-induced fissures. This is then used to determine the presence and thickness of an impermeable layer, providing hydrogeological data for coal seam mining. However, the mechanical methods for determining floor mining-induced fissures are overly simplified, and empirical regression formulas are difficult to apply in engineering practice due to differences in the hydrogeological and mining conditions of the underlying data. Furthermore, existing technologies offer grouting reinforcement methods for floor fissures or impermeable layers, but these schemes are insufficiently detailed and targeted, failing to comprehensively consider the rock formations, lithology, and hydrogeology of the formation. Summary of the Invention

[0005] In order to solve the technical problems in the prior art of inaccurate determination of the depth of floor mining fissures and poor effectiveness of Ordovician limestone water treatment solutions, the present invention proposes an Ordovician limestone water treatment method based on hydrogeological detection, comprising the following steps:

[0006] S1. Conduct hydrogeological surveys to determine the coal seam floor elevation a and coal seam burial depth H, the top elevation d of the Ordovician limestone water layer, and the rock columnar shape from the coal seam to the Ordovician limestone water layer. Based on the rock columnar shape, determine the top elevation c of the Ordovician limestone water riser. Measure the cohesion and internal friction angle of each rock layer in the coal seam floor and calculate the average cohesion C and average internal friction angle. Determine the average bulk density γ of the rock formation; determine the maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf by referring to adjacent mined working faces or working faces with similar mining conditions;

[0007] The depth h of the floor mining fracture zone is determined based on the following formula

[0008]

[0009] S2. Correct the depth h of the floor mining fracture zone and calculate the average cohesion C and average internal friction angle of the rock formation within the depth h of the floor. According to the average cohesion C and the average internal friction angle Determine a floor mining fracture zone depth h3 using the formula in step S1;

[0010] If h3≤h, then the corrected depth h1 of the floor mining fracture zone is h1=h;

[0011] If h3>h, take the difference between the top elevation of the closest thick hard rock layer below the floor mining fracture zone depth h and the coal seam floor elevation as the corrected floor mining fracture zone depth h1;

[0012] S3. Determine the range of the aquiclude, h2, as the rock layer between the corrected floor mining fracture zone and the top of the Ordovician limestone water conduction zone, and identify the mudstone and sandstone layers within the aquiclude. Directional drilling is performed into the sandstone layer of the aquiclude below the working face. The horizontal section of the directional drilling is first constructed in the sandstone layer below the uppermost mudstone layer within the aquiclude. During drilling, the presence of primary fractures in the sandstone layer is determined based on drilling phenomena, and grouting is performed based on the determination. Using the same method, horizontal drilling sections are sequentially constructed into the sandstone layer below the next mudstone layer within the aquiclude, and grouting is performed as needed until the sandstone layer above the lowermost mudstone layer is reached.

[0013] S4. Mining the coal within the working face to determine the strike range k of the advance support pressure. Before mining the working face to a distance k from the primary fracture, drill holes along the coal seam directly above the primary fracture within a range k / 2 in front and behind the strike to relieve the coal seam pressure through hydraulic fracturing.

[0014] S5. After the working face passes through the original cracks, a set of water retaining dams and drainage pipes shall be constructed.

[0015] Furthermore, in step S2, if h3≤h, based on safety considerations, the corrected floor mining fracture zone depth h1 is taken as: the difference between the floor burial depth of the deepest rock layer reached by the floor mining fracture zone depth h and the coal seam floor burial depth.

[0016] Furthermore, in step S2, if h3>h, as a parallel solution, the rock layers are accumulated layer by layer on the basis of the rock layers within the bottom plate depth h range, and the average cohesion C and average internal friction angle of the accumulated rock layers are calculated. According to the average cohesion C and the average internal friction angle at this time The depth h4 of the floor mining fracture zone is determined by the formula in step S1 until h4≤h+accumulated rock layer thickness, and finally the sum of h+final accumulated rock layer thickness is taken as the corrected depth h1 of the floor mining fracture zone.

[0017] Among them, in step S3, directional drilling is constructed in the second return air channel, and the directional drilling holes are arranged at intervals along the working face. The horizontal section of the directional drilling holes passes through the entire dip range of the bottom plate mining fracture zone corresponding to the working face, and the directional drilling holes are arranged in a one-hole, multi-layer manner.

[0018] Among them, in step S3, when encountering a primary fissure during the drilling process, the drilling fluid will advance rapidly in a short period of time. If the drilling fluid is not completely lost and only carries granular debris back into the slurry, the primary fissure is not connected to the Ordovician lime water. Grouting is performed to seal the primary fissure, and drilling is continued after the slurry solidifies. If the drilling fluid continues to increase and the concentration becomes thinner, and at the same time carries granular debris back into the slurry, the primary fissure is connected to the Ordovician lime water. Grouting is performed to seal the primary fissure, and drilling is continued after the slurry solidifies.

[0019] Furthermore, in step S5, the combined construction method of the water retaining dam and the drainage pipe is as follows: between the hydraulic support and the scraper conveyor, a first trench is constructed on the coal seam floor along the inclination of the working face, and a drainage pipe is buried therein, and a steel frame is arranged between the drainage pipe and the first trench; then a second trench is constructed in the same manner at a certain interval, and a grouting flower pipe is buried therein, and a steel frame is arranged between the grouting flower pipe and the second trench.

[0020] The inventive points and beneficial effects of the present invention are as follows: 1. The present invention is based on hydrogeological exploration, and corrects the calculation results of the bottom plate fracture zone depth, taking into account the lithology and layered characteristics of the rock strata, so that the corrected bottom plate fracture zone depth calculation results are more accurate and have stronger practical engineering application significance. It solves the problem of the existing technology of arbitrarily adding a certain thickness as a safety thickness without any basis after calculation through a formula, and thus the present invention can more accurately determine the thickness of the aquiclude.

[0021] 2. Aiming at the treatment of the pressurized aquifer - Ordovician lime water, the present invention adopts a comprehensive treatment plan of integrated detection and pre-reinforcement (prevention) → advanced pressure relief (re-prevention) → integrated water interception and drainage (compensation). Moreover, each step of the treatment plan is constructed based on the actual hydrogeological detection situation, which is the right remedy for the situation, improves the treatment effect of Ordovician lime water, and ensures safe production on the working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the inclined cross section of the Ordovician limestone water treatment method based on hydrogeological exploration according to the present invention;

[0023] Figure 2 Schematic diagram (top view) of the Ordovician limestone water treatment method based on hydrogeological exploration according to the present invention;

[0024] In the figure, coal seam 1, second return air lane 2, transport lane 3, working face 4, first return air lane 5, directional drill hole 6, floor mining fracture zone 7, mudstone layer 8, sandstone layer 9, Ordovician limestone water riser 10, Ordovician limestone water layer 11, goaf 12, retaining dam 13, drainage pipe 14, drainage ditch 15, and bedding drill hole 16;

[0025] a-coal seam floor elevation, b-bottom elevation of floor mining fracture zone, c-top elevation of Ordovician limestone water conduction zone, d-top elevation of Ordovician limestone water layer, h1-corrected depth of floor mining fracture zone, h2-thickness of aquiclude. DETAILED DESCRIPTION

[0026] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings. In the present invention, various aspects of the present invention are described with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present invention are not limited to those described in the accompanying drawings. It should be understood that the present invention is implemented by any of the various concepts and embodiments introduced above, as well as the concepts and implementation methods described in detail below, because the concepts and embodiments disclosed in the present invention are not limited to any implementation method. In addition, some aspects disclosed in the present invention can be used alone or in any appropriate combination with other aspects disclosed in the present invention.

[0027] like Figure 1-2 As shown, the method for treating Ordovician limestone water based on hydrogeological detection of the present invention comprises the following steps:

[0028] S1. Conduct hydrogeological surveys to determine the floor elevation a of the coal seam 1 affected by the confined aquifer, the Ordovician limestone layer 11, and the top elevation d of the Ordovician limestone layer. Core drilling is performed to determine the rock columnar profile from the coal seam 1 to the Ordovician limestone layer 11. Based on the rock columnar profile, the lithology and thickness / elevation of each stratum can be determined to determine the top elevation c of the Ordovician limestone water conduction zone (the Ordovician limestone water conduction zone is a permeable sandstone layer 9). The Ordovician limestone water conduction zone 10 can develop as far as the nearest mudstone layer 8 above the Ordovician limestone layer 11.

[0029] The coal seam burial depth H is determined based on the coal seam floor elevation a and the ground surface elevation. The cored rock samples are made into standard specimens to measure the cohesion and internal friction angle of each rock layer in the lower floor of coal seam 1 (here specifically the rock layer in the floor between coal seam 1 and the Ordovician limestone layer 11), and the average cohesion C and average internal friction angle of the entire floor rock layer are calculated. Determine the average bulk density γ of the rock formation; determine the maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf by referring to the adjacent mined working face or the working face with similar mining conditions; the average cohesion C of the entire floor rock formation can be approximately calculated by the following method: the sum of the product of the thickness of each rock layer and its cohesion, divided by the total thickness of each rock layer; the average internal friction angle The same method can be used to calculate the average bulk density γ;

[0030] The depth h of the floor mining fracture zone is determined by referring to the calculation formula in the paper "On the Depth and Distribution Characteristics of Coal Seam Floor Mining Fracture Zone, Zhang Jincai, Journal of China Coal Society, 1990". The calculation formula is:

[0031]

[0032] S2. Correct the floor mining fracture zone depth h obtained in step S1 to obtain a corrected floor mining fracture zone depth h1; the correction method is: calculate the average cohesion C and average internal friction angle of the rock formation within the floor depth h determined in step S1 According to the average cohesion C and the average internal friction angle Determine a floor mining fracture zone depth h3 using the formula in step S1;

[0033] If h3≤h, then h1=h. Furthermore, considering the layered characteristics of the stratum (similar to a plate), when a certain rock layer is affected by mining and cracks are generated in part (or plastic deformation occurs), its overall strength has been greatly reduced. Based on safety considerations, it is believed that the entire longitudinal direction of the rock layer will produce cracks (or plastic deformation occurs). That is, the final corrected floor mining crack zone depth h1 can be taken as: the deepest rock layer reached by the floor mining crack zone depth h calculated according to the formula in step S1 The difference between the floor burial depth and the coal seam floor burial depth; for example, the floor mining fracture zone depth h determined based on step S1 is 15m, and the thicknesses of the first five rock layers from the coal seam floor downward are 3m, 4m, 3m, 2m, and 4m respectively. Then, the floor mining fracture zone determined based on step S1 can reach the upper 3m position of the fifth rock layer. At this time, for safety reasons, we believe that the fifth rock layer will be completely destroyed or plastically deformed. The final corrected floor mining fracture zone depth h1 is 16m;

[0034] If h3>h, then continue to accumulate rock layers downward layer by layer based on the rock layers within the bottom plate depth h range, and calculate the average cohesion C and average internal friction angle of the accumulated rock layers. According to the average cohesion C and the average internal friction angle at this time Determine a floor mining fracture zone depth h4 by the formula in step S1, until h4≤h+accumulated rock layer thickness, and finally take the sum of h+final accumulated rock layer thickness as the corrected floor mining fracture zone depth h1; this calculation method is relatively conservative, and is suitable for geological conditions where the distance between the coal seam 1 and the Ordovician ash water layer 11 is large and the coal seam is shallow; as a parallel solution, a safety value can be added to h, and the safety value is the distance from the floor mining fracture zone depth h to the top of the closest thick hard rock layer below it. The thick hard rock layer can be determined with reference to the concept of key layer, and can refer to a rock layer with large average compressive and shear strength, and relatively large thickness, that is, the overall strength of the rock layer is large and not easy to destroy, that is, the floor mining fracture zone is finally taken. The difference between the top elevation of the closest thick hard rock layer below the gap zone depth h and the elevation of the coal seam floor is used as the corrected floor mining fracture zone depth h1; for example, the floor mining fracture zone depth h determined based on step S1 is 15m, and the thicknesses of the first 7 rock layers from the coal seam floor downward are 3m, 4m, 3m, 2m, 3m, 2m (mudstone), and 4m (sandstone), respectively. The floor mining fracture zone determined based on step S1 is the first 5 rock layers, the 6th rock layer is a sandstone layer with a smaller thickness and lower strength (low strength and thin thickness are easily affected by mining stress and damaged), and the 7th rock layer is a sandstone layer with a larger thickness and higher strength (large strength and thickness are not easily damaged by mining stress), that is, the safety value is 2m, and the corrected floor mining fracture zone depth is 17m.

[0035] S3. Determine the range h2 of the aquiclude, where h2 is the rock layer between the corrected floor mining fracture zone 7 and the top of the Ordovician limestone water conduction zone 10 determined in step S2. The mudstone layer 8 within the aquiclude and the sandstone layer 9 between the mudstone layer 8 are also determined. It should be noted that the mudstone layer 8 and sandstone layer 9 herein are general terms. The mudstone layer 8 generally refers to rock layers with water-isolating properties, such as shale, similar to mudstone, and the sandstone layer 9 generally refers to rock layers with water-permeability, such as conglomerate, similar to sandstone.

[0036] Arrange the mining face, including arranging the return air lane 5 (first return air lane), the transport lane 3, and the return air lane 2 (second return air lane) of the next working face in the working face 4;

[0037] In the return air lane of the next working face adjacent to the working face 4, i.e., the second return air lane 2, a directional drill hole 6 is constructed in the sandstone layer 9 of the aquiclude below the working face 4. The directional drill holes are arranged at intervals along the direction of the working face 4. The directional drill holes 6 include a vertical section and a horizontal section, wherein the horizontal section runs through the entire inclination range of the bottom plate mining fracture zone 7 corresponding to the working face 4. The horizontal section of the directional drill hole is constructed from the second return air lane 2 to the return air lane of the working face 4, i.e., the first return air lane 5. The directional drill hole 6 can be arranged in a one-hole, multi-layer manner. The horizontal section is first constructed in the sandstone layer 9 below the uppermost mudstone layer 8 in the aquiclude. During the drilling process, it is judged based on the drilling phenomenon whether there are primary fractures in the sandstone layer passed through (common ones are faults, When drilling into a primary fracture, the drilling fluid will advance rapidly in a short period of time. For example, when drilling into the gap between faults and collapsed columns, if the drilling fluid is not completely lost and only carries granular debris back into the slurry (derived from the gravel inside the fault, collapsed column and other structures), then the primary fracture is not connected to the Ordovician limestone water. Grouting is required to seal the primary fracture and continue drilling after the slurry solidifies. If the amount of drilling fluid does not decrease but increases and the concentration becomes thinner, and the drilling fluid carries granular debris back into the slurry (derived from the gravel inside the fault, collapsed column and other structures), then it can be determined that the primary fracture (fault, collapsed column) encountered in the drilling is connected to the Ordovician limestone water. Grouting is required to seal the primary fracture and continue drilling after the slurry solidifies.

[0038] The injected slurry can be cement slurry or a mixture of cement slurry and fly ash. Grouting can be done by full-hole section grouting or local grouting using an isolation device. For example, a plugging bag is set near the end of the grouting drill pipe, and the grouting drill pipe is lowered to the crack. A dual grouting solution (such as water glass and calcium chloride solution) is injected into the plugging bag. After the dual grouting solution solidifies, grouting is then injected from the grouting drill pipe cavity into the original crack.

[0039] The same method is used to construct horizontal drilling sections in the sandstone layer 9 below the next mudstone layer 8 in the aquiclude, and grouting is performed as needed until the sandstone layer 9 above the lowest mudstone layer 8; Figure 1 As shown, the aquiclude includes three mudstone layers 8 and three sandstone layers, and the horizontal drilling sections are constructed in the sandstone layer 9 below the uppermost mudstone layer and in the sandstone layer above the lowermost mudstone layer 9 respectively;

[0040] S4. Mining the coal in the working face 4, monitoring the maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf during the mining process, and recalculating the floor mining fracture zone depth h1 based on the measured maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf according to steps S1-S2, ensuring that the error between the calculated result and the floor mining fracture zone depth h1 calculated by referring to the maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf determined by the adjacent mined working face or the working face with similar mining conditions is small, and ensuring that the thickness of the impermeable layer can achieve the water-proof effect; otherwise, the coal seam 1 can be pre-drilled in the seam 1 along the seam to relieve the pressure of the coal seam 1 by hydraulic fracturing to reduce the maximum support pressure coefficient n;

[0041] Determine the range of the advance support pressure. Assuming that the length along the strike is k, before the working face is mined to a horizontal distance k from the primary fissure detected in step S3, construct a bed drill hole 16 in the coal seam 1 within a range of k / 2 before and after the primary fissure along the strike. The bed drill hole 16 can be constructed from the first return air lane 5, or from the transport lane 3, or from the first return air lane 5 and the transport lane 3 at intervals along the strike. After the bed drill hole 16 is constructed, the coal seam 1 is decompressed by hydraulic fracturing to reduce the maximum support pressure coefficient n, thereby reducing the depth of the floor mining fracture zone 7 at the primary fissure of the aquifer, and avoiding activation of the reinforced primary fissure of the aquifer.

[0042] S5. Along the advancing direction of the working face 4, a combination of a water retaining dam 13 and a drainage pipe 14 is constructed at a certain interval, and a group of water retaining dams 13 and drainage pipes 14 must be constructed after pushing through the original fissures. The construction method of the water retaining dam and drainage pipe combination is: between the hydraulic support and the scraper conveyor, a rectangular first trench is constructed on the coal seam bottom plate along the inclination of the working face, and a circular drainage pipe 14 is buried therein. A rectangular steel frame is arranged between the drainage pipe 14 and the first trench to support the first trench and protect the drainage pipe 14. The drainage pipe is located in the rectangular steel frame. The size of the rectangular steel frame is consistent with the size of the rectangular first trench, which supports the first trench and reduces the damage to the bottom plate caused by the excavation of the first trench. At the same time, the consistent size can make the top of the steel frame compensate for the unevenness of the bottom plate caused by the excavation of the first trench, that is, the steel frame can ensure the flatness of the bottom plate after the first trench is excavated, avoiding affecting the advancement of the hydraulic support; then a rectangular steel frame is constructed in the same way at a certain interval. The second groove is provided with a grouting flower pipe buried therein, and a rectangular steel frame is arranged between the grouting flower pipe and the second groove to support the second groove and protect the grouting flower pipe. The grouting flower pipe is located in the rectangular steel frame, and the size of the rectangular steel frame is consistent with the size of the rectangular second groove, so as to support the second groove and reduce the damage to the bottom plate caused by the excavation of the second groove. At the same time, the consistent size can make the top of the steel frame compensate for the unevenness of the bottom plate caused by the excavation of the second groove, that is, the steel frame can ensure the flatness of the bottom plate after the excavation of the second groove, and avoid affecting the advancement of the hydraulic support; the spacing between the first groove and the second groove is not less than the slurry diffusion radius during grouting of the grouting flower pipe in the second groove. After the working face pushes a certain distance through the second groove, cement slurry is injected into the goaf 12 through the grouting flower pipe in the first return air lane 5, and the cement slurry forms a water dam 13 together with the rock blocks in the collapse zone of the goaf nearby. The drainage pipe 14 also adopts a flower pipe, and its lower end is connected to the drainage ditch 15 of the transport lane;

[0043] After the original fissures are activated by mining, if there is ash water penetrating the aquiclude and entering the goaf 12 from the bottom plate mining fissure zone 7, the water retaining dam 13 can block the water gushing out from the original fissures in the goaf, preventing it from entering the mining area where the hydraulic support is located. At the same time, the drainage pipe 14 can drain the water intercepted by the water retaining dam 13 to the drainage ditch 15 for discharge.

[0044] While the present invention has been described above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for treating Ordovician limestone water based on hydrogeological exploration, characterized in that: The steps include: S1. Conduct hydrogeological surveys to determine the coal seam floor elevation a and coal seam burial depth H, the top elevation d of the Ordovician limestone water layer, and the rock columnar shape from the coal seam to the Ordovician limestone water layer. Based on the rock columnar shape, determine the top elevation c of the Ordovician limestone water riser. Measure the cohesion and internal friction angle of each rock layer in the coal seam floor and calculate the average cohesion C and average internal friction angle. Determine the average bulk density γ of the rock formation; determine the maximum support pressure coefficient n and the pressure reduction coefficient m of the goaf by referring to adjacent mined working faces or working faces with similar mining conditions; determine the depth h of the floor mining fracture zone based on the following formula S2. Correct the depth h of the floor mining fracture zone and calculate the average cohesion C and average internal friction angle of the rock formation within the depth h of the floor. According to the average cohesion C and the average internal friction angle Determine a floor mining fracture zone depth h3 using the formula in step S1; if h3 ≤ h, then the corrected floor mining fracture zone depth h1 is h1 = h; if h3 > h, then take the difference between the top elevation of the thick hard rock layer closest to the floor mining fracture zone depth h and the coal seam floor elevation as the corrected floor mining fracture zone depth h1; If h3>h, as a parallel solution, continue to accumulate rock layers downward layer by layer based on the rock layers within the bottom plate depth h, and calculate the average cohesion C and average internal friction angle of the accumulated rock layers. According to the average cohesion C and the average internal friction angle at this time Determine a floor mining fracture zone depth h4 using the formula in step S1 until h4 ≤ h + accumulated rock layer thickness, and finally take the sum of h + the final accumulated rock layer thickness as the corrected floor mining fracture zone depth h1; S3. Determine the range of the aquiclude, h2, as the rock layer between the corrected floor mining fracture zone and the top of the Ordovician limestone water conduction zone, and identify the mudstone and sandstone layers within the aquiclude. Directional drilling is performed into the sandstone layer of the aquiclude below the working face. The horizontal section of the directional drilling is first constructed in the sandstone layer below the uppermost mudstone layer within the aquiclude. During drilling, the presence of primary fractures in the sandstone layer is determined based on drilling phenomena, and grouting is performed based on the determination. Using the same method, horizontal drilling sections are sequentially constructed into the sandstone layer below the next mudstone layer within the aquiclude, and grouting is performed as needed until the sandstone layer above the lowermost mudstone layer is reached. S4. Mining the coal within the working face to determine the strike range k of the advance support pressure. Before mining the working face to a distance k from the primary fracture, drill holes along the coal seam directly above the primary fracture within a range k / 2 in front and behind the strike to relieve the coal seam pressure through hydraulic fracturing. S5. After the working face passes through the original cracks, a set of water retaining dams and drainage pipes are constructed.

2. The method for treating Ordovician limestone water based on hydrogeological exploration according to claim 1, characterized in that: In step S2, if h3≤h, based on safety considerations, the corrected floor mining fracture zone depth h1 is taken as: the difference between the floor burial depth of the deepest rock layer reached by the floor mining fracture zone depth h and the coal seam floor burial depth.

3. The method for treating Ordovician limestone water based on hydrogeological exploration according to claim 1, characterized in that: In step S3, directional drilling is constructed in the second return air lane. The directional drilling holes are arranged at intervals along the working face. The horizontal section of the directional drilling holes passes through the entire dip range of the bottom plate mining fracture zone corresponding to the working face. The directional drilling holes are arranged in a one-hole, multi-layer manner.

4. The method for treating Ordovician limestone water based on hydrogeological exploration according to claim 1 or 3, characterized in that: In step S3, when encountering a primary fissure during the drilling process, the drilling fluid will advance rapidly in a short period of time. If the drilling fluid is not completely lost and only carries granular debris back into the slurry, the primary fissure is not connected to the Ordovician lime water. Grouting is performed to seal the primary fissure, and drilling is continued after the slurry solidifies. If the drilling fluid continues to increase and the concentration becomes thinner, and granular debris is carried back into the slurry, the primary fissure is connected to the Ordovician lime water. Grouting is performed to seal the primary fissure, and drilling is continued after the slurry solidifies.

5. The method for treating Ordovician limestone water based on hydrogeological exploration according to claim 1, characterized in that: In step S5, the combined construction method of the water retaining dam and the drainage pipe is as follows: between the hydraulic support and the scraper conveyor, a first trench is constructed on the coal seam floor along the inclination of the working face, and a drainage pipe is buried therein, and a steel frame is arranged between the drainage pipe and the first trench; then a second trench is constructed in the same manner at a certain interval, and a grouting flower pipe is buried therein, and a steel frame is arranged between the grouting flower pipe and the second trench.

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